This invention relates to a leach resistant antimicrobial fabric and a process for making such a fabric.
A need exists for a pillow ticking, hospital gown, surgical drape or like product that provides permanent antimicrobial capacity yet the antimicrobial agent is not extracted (leached) from the fabric in use. A need also exists for such a product that is water and solvent repellent.
A particularly useful antimicrobial agent is DC-Q9-5700 available from Dow Corning Corporation of Midland, Mich. The material is a silicone quaternary amine, chemically 3(trimethoxysilyl)propyloctadecyl dimethyl ammonium chloride, and is typically supplied in a 42% solids solution. This material has been used to protect textiles and inhibit odor-causing bacteria and fungi which contamination may result in odor problems, discoloration and deterioration of these textiles. Application of this type of silicone quaternary amine onto the surface of textiles has been found to inhibit the growth of microorganisms and to aid in the control of the above-mentioned problems. As such it is authorized by the Environmental Protection Agency of the U.S. Government for use on textile surfaces (EPA No. 34292-1) and it has also been accepted by the Food and Drug Administration of the U.S. Government for use in medical device/non-drug applications for use with humans and animals.
Surgical drapes, hospital gowns, pillow ticking and like materials are typically made of non-woven textiles or other non-woven type materials. Antimicrobial agent such as DC-Q9 5700 when in dilute water solution and impregnated into a nonwoven cellulose web having an acrylic binder reacts slowly with the hydroxyl groups of the cellulose and acrylic binder because of the diluteness. When dried at 320.degree. F. at practical machine running speeds, incomplete crosslinking takes place and the antimicrobial agent can be leached out. Crosslinking materials such as melamine formaldehyde have little or no effect on this leaching out problem. In addition, when pigment binder, such as polyvinyl alcohol, is used in conjunction with the antimicrobial agent in color (pigment) baths, the binder will leach out under the same conditions as described above. Crosslinkers such as melamine formaldehyde again have little or no effect on this leaching out problem.
Normally, a silicone quaternary amine such as DC-Q9-5700 needs a surface that has --OH funtionality, such as glass, cellulose or polyester fibers. Therefore, it has not previously been possible to apply such a silicone quaternary amine to a nonwoven substrate, such as polypropylene, which has no --OH functionality present on the fibers. Furthermore, the treatment of a nonwoven fabric with a silicone quaternary amine requires sufficient time and temperature for a proper cure in order to obtain a leach resistant product. Therefore, the treatment of low temperature melting or low temperature softening webs, such as polypropylene fiber or polyethylene fiber webs with the antimicrobial has not previously been possible.
It has previously been found that the addition of a fluoropolymer to a non-woven fabric impregnated with DC-Q9-5700 will serve to made the fabric water and alcohol-repellent. This repellency is beneficial in that the fabric can then repel body fluids, alcohol and like liquids typically present in a hospital environment.
The requirements for a successful medical fabric or substrate include the following:
1. Bioactivity-the substrate must be bioactive, that is it should be bactericidal and not merely bacteriostatic. The substrate should preferably achieve about a 95% or better bactericidal effect within one hour.
2. Non-leachibility-the bioactive material must remain on the substrate and not be leached from the substrate, but if leaching occurs it must be virtually undetectable, i.e., only less than 0.2 parts per million (0.2 ppm) from a 81/2 inch.times.11 inch swatch. Additionally, when pigment binder is used in conjunction with the antimicrobial agent in color baths, the binder must remain on the substrate and not be leached out.
Furthermore, if water repellency is a desired property, then the fabric should be water repellent as measured by (INDA) test IST 80.7-70(R77), referred to herein as the mason jar test. In this test a swatch of sample fabric is placed over the mouth of a mason jar containing sufficient normal saline (0.9% NaCl) that when the jar is inverted a 4.5" head of water results. The top ring is screwed onto the jar, the jar is inverted and placed on a glass plate. The inverted jar is observed and the time is measured until the jar leaks. The minimum time for a successful sample is 45 minutes; however, the average time for successful samples is at least about one hour.
Accordingly, it is an object of this invention to provide a bioactive, leach-resistant nonwoven fabric.
It is a further object of this invention to provide such a fabric that is water and alcohol repellent.
It is a further object of this invention to provide such a fabric having a substrate with no OH functionality, such as polypropylene.
It is a still further object of this invention to provide such a fabric having a substrate with a low melting or softening temperature, such as polypropylene or polyethylene.